Method for vacuum treatment of workpieces and vacuum treatment facility

ABSTRACT

A lock chamber ( 1 ) is isolated from the environment (U) by a lock-valve ( 3 ) and from a vacuum chamber configuration ( 7 ) by a lock valve ( 5 ). A turbo vacuum pump ( 13 ) acts upon the vacuum chamber configuration ( 7 ). An additional pump ( 9/15 ) is switchably ( 17 ) connected downstream from the pump, which switchably operates either as a prevacuum pump for the turbo vacuum pump ( 13 ) or as lock chamber pump.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a method for the vacuum treatment ofworkpieces, in which a workpiece is introduced into an interlock chamberopen to the ambient atmosphere, the interlock chamber is pumped outafter it had been closed off from said ambient atmosphere, the interlockchamber is opened into an at least partially pumped-off vacuum chamberconfiguration, the workpiece subsequently is transported from theinterlock chamber into the configuration and treated in theconfiguration, the workpiece subsequently is transported back from theconfiguration into the interlock chamber, the interlock chamber isclosed against the configuration, is subsequently flooded and, lastly,the treated workpiece is carried from the flooded interlock chamber intothe ambient atmosphere, wherein at least a portion of the configurationis pumped out by means of a turbo vacuum pump with a forevacuum pumpoperationally connected therewith at the high-pressure side and theinterlock chamber is pumped out by means of an interlock pump.

The present invention relates further to a vacuum treatment installationcomprising an interlock chamber, an interlock pump connected therewith,further communicating with the interlock chamber a vacuum chamberconfiguration operationally connected with at least one turbo vacuumpump, with which latter is associated at the high-pressure side aforevacuum pump.

In FIG. 1 is depicted in the form of a function block diagram one suchprior known configuration, in which said prior known workpiece treatmentmethod is readily evident to a person skilled in the art.

According to FIG. 1, an interlock chamber 1 with lock valve 3 againstambient atmosphere U is provided with a lock valve 5 against a vacuumchamber configuration 7. The vacuum chamber configuration 7 can thereincomprise as a minimum configuration a single treatment chamber B or oneor several transport chamber(s) operationally connected with the latter,again, one or several treatment chamber(s) B as well as, if appropriatefurther interlock chambers depending on how complex the treatment to becarried out on the workpieces is and how many steps it comprises. As isreadily familiar to a person skilled in the art, the workpieces areintroduced into the interlock chamber 1 with the lock valve 5 closed andlock valve 3 is opened, whereupon the lock valve 3 is closed and theinterlock chamber 1 is evacuated by means of an interlock pump 9, suchas for example a single- or multistage rotary vane pump and via a valve11.

In principle, on the vacuum chamber configuration 7 at least one turbovacuum pump 3 is provided, which pumps out at least the one treatmentchamber, if appropriate jointly in combination with a transport chamberassociated with this treatment chamber. If several treatment chambersare provided which are to be pumped independently of one another, it isentirely possible to provide several turbo vacuum pumps 13.

SUMMARY OF THE INVENTION

The at least one turbo vacuum pump 13, operationally connected with thevacuum chamber configuration 7, is succeeded at the high-pressure sideby a forevacuum pump 15, in order to generate the required forepressureat the turbo vacuum pump 13.

It is the task of the present invention to further develop the method ofthe above described type such that it becomes cost-effective and that itbecomes less susceptible to fault, further to simplify the installationof said type accordingly, and to realize it such that it requires lessmaintenance and has greater compactness. This is achieved with themethod of said type thereby that as the forevacuum pump the interlockpump is operationally connected with the turbo vacuum pump.

To solve said task the vacuum treatment installation of the abovedescribed type is distinguished thereby that the forevacuum pump,associated with the turbo vacuum pump, is the interlock pump. The methodaccording to the invention as well as also the configuration accordingto the invention are in particular well suitable for the treatment, inparticular coating, of disk-shaped workpieces, in particular of storagedisks, therein especially of optical data storage disks.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will subsequently be explained in conjunction withFigures. Therein depict:

FIG. 1 is a function block diagram of a prior art method,

FIG. 2 building on a representation according to FIG. 1, the fundamentalfurther development according to the invention of the vacuuminstallation for realizing the production method according to theinvention,

FIG. 3 schematically the realization of a highly compact vacuumtreatment installation according to the invention in a preferredembodiment.

Using the same reference symbols, in FIG. 2 the same vacuum treatmentinstallation as depicted in FIG. 1, however, as will be described in thefollowing, is further developed according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to FIG. 2 the forevacuum pump succeeding the turbo vacuum pump13 at the high-pressure side is omitted. In its place the interlock pump9 is also employed as the forepump of the turbo vacuum pump 13.Therefore, in FIG. 2 the interlock/forevacuum pump used in combinationis denoted by the combined reference symbol 9/15. In terms of signaltechnology thus the low-pressure side of the interlock-/forevacuum pump9/15 is operationally connected via a controlled switch-over device 17with the interlock chamber as well as also with the high-pressure sideof the turbo vacuum pump 13. When loading a workpiece into the interlockchamber 1, for pumping out the interlock chamber 1 the low-pressureinput of the interlock-/forevacuum pump 9/15 is isolated via theswitch-over unit 17 from the high-pressure port of the turbo vacuum pump13 and operationally connected with the interlock. After pumping out theinterlock chamber 1 to transfer pressure to the vacuum chamberconfiguration 7, the low-pressure input of the interlock-/forevacuumpump 9/15 is operationally connected via said switch-over device 17 withthe high-pressure side of the turbo vacuum pump 13.

It is entirely possible to realize the switch-over configuration 17, asindicated in dashed lines at 17 a and 17 b, by means of valvescontrollable independently of one another, or by means of a two-wayvalve such as the device 17 is also depicted.

The control of said operational connections can therein take place underpressure control, for example by measuring the pressure in the interlockchamber 1 and switching-over to forepump operation of theinterlock-/forevacuum pump 9/15 upon reaching a predetermined pressurevalue or it can take place at a predetermined periodicity according topre-ascertained cycles.

Preferably a turbo vacuum pump 13 is employed which at the high-pressureside can work against a maximally high pressure, preferably of at least1 mbar, in particular preferred of at least 10 mbar. For this purposeare especially suitable turbo drag pumps or turbo pumps combined withHolweck stages at the pump output. As the interlock-/forevacuum pump,furthermore, a single- or multistage rotary vane pump is preferablyused.

When applying said preferably used turbo vacuum pump 13 this evenpermits using a very “clean” membrane pump as the interlock-/forevacuumpump.

Furthermore, the interlock chamber 1 should be pumped out as rapidly aspossible such that at the high-pressure side the turbo vacuum pump 13does not need to operate too long in the operational connection, whichin this case is closed, to the switch-over configuration 17 or to aclosed valve 17 a. Accordingly is dimensioned, on the one hand, thecapacity of the provided interlock-/forevacuum pump 9/15, but inparticular the volume of the interlock chamber 1. The latter should beselected to be of minimum size, the ratio of the interlock chambervolume to the volume pumped out by the provided turbo vacuum pump 13should be selected to be maximally 1:40, preferably even maximally1:100.

In FIG. 3 is depicted schematically a preferred, highly compact vacuumtreatment installation according to the invention for the vacuumtreatment according to the invention of workpieces, in particularcircular disk-shaped workpieces, such as for example, and preferably, ofdata storage disks.

In a housing 7 a of the vacuum chamber configuration 7 a transportdevice 21 is provided driven rotationally movable about an axis A bymeans of a drive 20, with transport arms 23 bent off at an angle withrespect to the axis of rotation A. By means of associated linear drives,such as shown at 25, the transport arms 23 are encapsulated, extendableand retractable, as shown by F. At their ends they support workpiececarrier plates 27 for (not shown) workpiece disks. The vacuum chamberconfiguration 7 comprises a working station 28, for example flanged ontothe housing 7 a, a working station 29, such as for example a sputterstation.

The volume of a provided interlock chamber la is minimized thereby thatit is virtually integrated into the section thickness of the wall of thehousing 7 a. This minimization, previously already discussed inconjunction with FIG. 2, of the interlock chamber volume is possible inthe extent depicted in FIG. 3, in particular in combination with thetreatment, for example in particular of the coating, of disk-shapedworkpieces, in particular of storage disks, therein especially ofoptical data storage disks.

With the depicted installation according to the invention in particularaccording to FIG. 3, cycle times, for example, of less than 2 secondswere attained in the CD production or the production of optical storagedisks, concretely of 1.8 seconds at a lock passing time of 0.4 seconds.

Fundamentally it is preferably proposed that the sub-interval range ofthe cycle time “transportation and treatment” is at least 50% of thetotal cycle time, preferably at least 60%, or expressed with respect tothe “lock passage time”, at least 300%.

The outer lock valve is denoted by 3 a, the inner one is formed by theworkpiece carrier plate 27 on the particular transport arm 23. Byrotation of the transport device 21 about axis A, the provided transportarms or the retracted carrier plates 27 are first placed into positiononto interlock chamber 1 a and working station 29. By extending the armsthe corresponding stations 1 a, 29 are sealed off, either by setting upa pressure stage, such as by means of labyrinth sealing, orvacuum-tight, for example form-fittingly. On the one hand, in this caseat the interlock chamber 1 a by opening the lock valve 3 a a workpieceis input or output, while simultaneously at the working station 29,either closed or sealed according to the requirements, the workpieceworking takes place.

A configuration of this type is fully described in EP A 0 518 109corresponding to U.S. Pat. No. 5,245,736 by the applicant as well as inthe present application.

As is evident, the switch-over device 17, described in conjunction withFIG. 2, is preferably realized by means of valves 17 b′ or 17 a′inserted into the connection line. In the embodiment depicted, the turbovacuum pump 13 pumps out the interior volume of the transport chamber aswell as also the process chamber. A ratio of the volumes of interlockchamber 1 a to the volume pumped out by the turbo vacuum pump 13 of1:110 was realized.

In FIG. 3, 31 denotes a flooding valve for the interlock chamber 1 a, 33the flooding valve, already depicted in FIGS. 1 and 2, for the turbovacuum pump 13.

What is claimed is:
 1. A method for vacuum treatment of workpieces,comprising: a) introducing a workpiece into an interlock chamber (1)that is open to an ambient atmosphere (U); b) pumping out the interlockchamber (1) after the interlock chamber has been closed (3) against saidambient atmosphere; c) opening the interlock chamber into a vacuumchamber configuration (7) which is at least partially pumped out; d)transporting the workpiece from the interlock chamber (1) into theconfiguration (7); e) treating the workpiece in the configuration (7);f) transporting the workpiece back from the configuration (7) into theinterlock chamber (1); g) closing (5) the interlock chamber (1) againstthe configuration (7), and subsequently flooding the interlock chamber;h) carrying the treated workpiece from the flooded interlock chamber (1)into the ambient atmosphere (U); i) pumping out at least a portion ofthe configuration (7) by means of a turbo vacuum pump (13) with aforevacuum pump (15) operationally connected therewith at ahigh-pressure side of the turbo vacuum pump; j) pumping out at least aportion of the interlock chamber (1) by means of an interlock pump (9);and k) operationally connecting the interlock pump (9) to the turbovacuum pump (13) to act as the forevacuum pump (15) with a ratio of theinterlock chamber volume to be pumped to a volume to be pumped by meansof the turbo vacuum pump (13) being maximally 1:40.
 2. A method asclaimed in claim 1, wherein, as the interlock and forevacuum pump(9/15), a single or multistage rotary vane or membrane pump is employed.3. A method as claimed in claim 1, wherein the turbo vacuum pump (13) atthe high-pressure side works against a pressure of at least 1 mbar.
 4. Amethod as claimed in claim 3, wherein the turbo vacuum pump (13) at thehigh-pressure side works against a pressure of at least 10 mbar and theturbo vacuum pump is a turbo drag or a turbo pump with Holweck stage. 5.A method as claimed in claim 1, wherein for pumping out the interlockchamber (1) at a low-pressure side, the forevacuum pump (9/15) isisolated (17, 17 a) from its operational connection with the turbovacuum pump (13), subsequently for pumping out the portion of theconfiguration (17, 17 b), the forevacuum pump (9/15) is isolated fromthe interlock chamber (1) and is connected at the high-pressure sidewith the turbo vacuum pump (13).
 6. A method as claimed in claim 1,wherein a low-pressure input of the interlock and the forevacuum pump(9/15) is sequentially operationally connected (17, 17 a, 17 b) to theinterlock chamber (1), and to the high-pressure output of the turbovacuum pump (13).
 7. A method as claimed in claim 6, wherein alow-pressure input of the interlock and the forevacuum pump (9/15) issequentially intermittently operationally connected to the interlockchamber (1) and to the high-pressure output of the turbo vacuum pump(13).
 8. A method as claimed in claim 1, wherein the ratio of the volumeof the interlock chamber (1) to be pumped out to that which is to bepumped out by means of the turbo vacuum pump (13) is selected to bemaximally 1:100.
 9. A method as claimed in claim 1 for coating adisk-shaped workpiece.
 10. A method as claimed in claim 1 for coating ofoptical storage disks, wherein a cycle time from the introduction of theworkpiece up to and including carrying away of the workpiece ismaximally 2 seconds.
 11. A method as claimed in claim 1, wherein a timerange for steps c) to g) is at least 50% of the time range for steps a)to h).
 12. A vacuum treatment installation comprising: an interlockchamber (1); an interlock pump (9) operationally connected to theinterlock chamber; a vacuum chamber configuration (7) communicating withthe interlock chamber (1) at least one turbo vacuum pump (13)operationally connected to the vacuum chamber configuration (7); aforevacuum pump (15) associated with a high-pressure side of the turbovacuum pump (13); the forevacuum pump (15) being associated with theturbo vacuum pump (13) is the interlock pump (9/15) and a ratio of theinterlock chamber volume to be pumped to the volume to be pumped bymeans of the turbo vacuum pump (13), is maximally 1:40.
 13. Aninstallation as claimed in claim 12, wherein the interlock andforevacuum pump (9/15) is a single or a multistage rotary vane pump or amembrane pump.
 14. An installation as claimed in claim 12, wherein theturbo vacuum pump (13) is disposed such that at the high-pressure sideit works against a pressure of at least 1 mbar.
 15. An installation asclaimed in claim 14, wherein the turbo vacuum pump (13) is disposed suchthat at the high-pressure side it works against a pressure of at least10 mbar and it is a turbo drag or turbo pump with Holweck stage.
 16. Aninstallation as claimed in claim 12, wherein a low-pressure input of theinterlock and forevacuum pump (9/15) is operationally connected via aswitch-over configuration (17, 17 a, 17 b) to the interlock chamber (1)and to the high-pressure output of the turbo vacuum pump (13).
 17. Aninstallation as claimed in claim 12, wherein the ratio of the interlockchamber volume to be pumped and the volume to be pumped by means of theturbo vacuum pump (13) is maximally 1:100.